A type of cyanometer. an instrument used to measure the blueness of the sky. The Linke-scale is simply a set of eight cards of different standardized shades of blue. They are evenly numbered 2 to 26. The odd numbers are used by the observer if he or she j ...

A unit of luminance or brightness equal to 1/d candles per foot'.

An area of low atmospheric pressure which has a closed circulation that is cyclonic (counterclockwise in northern hemisphere and clockwise in southern hemisphere).

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

Same as contact anemometer.

A device used to switch electrical current at a selectable setpoint temperature.

A recording hair hygrometer.

See mote.

An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

A pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil. See ram penetrometer.

Same as atmospheric pressure.

Amount of water, expressed as a depth or as a mass, which would be obtained if all the water vapor in a specified column of the atmosphere were condensed and precipitated.

The process by which water in plants is transferred as water vapor to the atmosphere. Also, the amount of water so transferred.

Radiation with wavelengths greater than 4 microns. (In meteorology, same as infrared radiation.)

See photometer.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifteenth contact of the commutator, up to a number determined by the design of the commutator, and each fifth contact thereafter. This signal is t ...

A hypothetical "body" whose surface absorbs no electromagnetic radiation of any wavelength. An idealization exactly opposite to that of the black body. In nature, no true white bodies are known. Moist white pigments exhibiting high reflectivity for visibl ...

A seasonal wind of persistent direction, characterized by a pronounced change in direction between seasons.

A balloon-borne instrument for the simultaneous measurement and transmission of meteorological data. It includes transducers for the measurement of pressure, temperature, and humidity; a modulator for the conversion of the output of the transducers to a q ...